Tip: A reamer is the correct tool to use for enlarging a tuner hole. You can work slowly and carefully and you won’t split the headstock like you might with a power drill.

Fig. 10. Yikes! The Gotoh threaded collar (left) is too short to reach its tuning machine through the headstock. Fortunately, taller collars and thinner washers (right) pirated from another set of tuners fit through the headstock and match the Gotoh threads. A close call.

Here’s where the project almost went off the rails. After I’d fitted the tuners into their snug, new holes and pushed them through the headstock, I was dismayed to discover that the supplied threaded collars were too short to reach the matching threads in the keys themselves. These collars secure the tuners to the headstock, so they’re essential. The problem? The Epi’s headstock was thicker than a typical Strat-style guitar. Fortunately, I found a set of longer collars (Fig. 10) I could pirate from another set of keys in my shop. We got lucky this time.

Tip: Always measure the thickness of the headstock before you purchase tuners.

Fig. 11. (left) To avoid marring the collar nut or headstock, always use a socket wrench—not an adjustable wrench—to install this type of tuner. Fig. 12. (right) Use a metal ruler to align the tuners with each other on the headstock.

Using a socket wrench, I installed the Gotoh tuners (Fig. 11). Don’t do this with an adjustable crescent wrench because it’s likely to slip off and butcher the nut or mar the headstock.With the collars moderately tight—but not completely torqued down—I then worked on aligning the tuners with each other. Once again, a 6" metal ruler comes in handy (Fig. 12).

Fig. 13. Measuring the drill bit against the tuner mounting screw. Once you’ve found the correct drill bit, mark the drill depth with a red Sharpie.

With the tuners now aligned and tightened against the headstock, it was time to drill holes for the tuner mounting screws. You must do this very carefully. For starters, use a drill bit that’s the same size as the screw shaft (Fig. 13). This leaves enough room for the screw threads to “tap” into the wood without splitting the headstock. If you drill the screw holes too small, inserting the screws can cause the headstock to crack. Never force the screws into the headstock.

Fig. 14. Confirming bit depth with the red guide mark. Remember to take the tuner’s screw eyelet
into account when measuring.

Here’s another trade secret: Mark the drill bit with a red Sharpie to illustrate the correct depth for the mounting holes, as shown in Fig. 13. Before drilling any holes, place the bit against the headstock. While taking into account the thickness of the eyelet that holds the mounting screw, determine how far the screw will penetrate the headstock (Fig. 14). The last thing you want to do is drill through the headstock!